Control of particulate entrainment by fluids

ABSTRACT

An aqueous slurry composition for use in industries such as petroleum and pipeline industries that includes: a particulate, an aqueous carrier fluid, a chemical compound that renders the particulate surface hydrophobic, and a small amount of an oil. The slurry is produced by rendering the surface of the particulate hydrophobic during or before the making of the slurry. The addition of the oil greatly enhances the aggregation potential of the hydrophobically modified particulates once placed in the well bore.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage under 35 U.S.C. §371 ofinternational application number PCT/CA2008/000786, filed on 25 Apr.2008, which is currently pending; international application numberPCT/CA2008/000786 is incorporated herein by reference in its entirety.International application number PCT/CA2008/000786 cites the benefit ofU.S. Application 60/924,006, filed 26 Apr. 2007, which is currentlyexpired; U.S. Application 60/924,006 is incorporated herein by referencein its entirety.

FIELD

This invention relates to fluid compositions and their use incontrolling proppant flowback after a hydraulic fracturing treatment andin reducing formation sand production along with fluids in poorlyconsolidated formations.

BACKGROUND

Hydraulic fracturing operations are used extensively in the petroleumindustry to enhance oil and gas production. In a hydraulic fracturingoperation, a fracturing fluid is injected through a wellbore into asubterranean formation at a pressure sufficient to initiate fractures toincrease oil and gas production.

Frequently, particulates, called proppants, are suspended in thefracturing fluid and transported into the fractures as a slurry.Proppants include sand, ceramic particles, glass spheres, bauxite(aluminum oxide), resin coated proppants, synthetic polymeric beads, andthe like. Among them, sand is by far the most commonly used proppant.

Fracturing fluids in common use include aqueous and non-aqueous onesincluding hydrocarbon, methanol and liquid carbon dioxide fluids. Themost commonly used fracturing fluids are aqueous fluids including water,brines, water containing polymers or viscoelastic surfactants and foamfluids.

At the last stage of a fracturing treatment, fracturing fluid is flowedback to the surface and proppants are left in the fractures to preventthem from closing back after the hydraulic fracturing pressure isreleased. The proppant-filled fractures provide high conductive channelsthat allow oil and/or gas to seep through to the wellbore moreefficiently. The conductivity of the proppant packs formed afterproppant settles in the fractures plays a dominant role in increasingoil and gas production.

However, it is not unusual for a significant amount of proppant to becarried out of the fractures and into the well bore along with thefluids being flowed back out the well. This process is known as proppantflowback. Proppant flowback is highly undesirable since it not onlyreduces the amount of proppants remaining in the fractures resulting inless conductive channels, but also causes significant operationaldifficulties. It has long plagued the petroleum industry because of itsadverse effect on well productivity and equipment.

Numerous methods have been attempted in an effort to find a solution tothe problem of proppant flowback. The commonly used method is the use ofso-called “resin-coated proppants”. The outer surfaces of theresin-coated proppants have an adherent resin coating so that theproppant grains are bonded to each other under suitable conditionsforming a permeable barrier and reducing the proppant flowback.

The substrate materials for the resin-coated proppants include sand,glass beads and organic materials such as shells or seeds. The resinsused include epoxy, urea aldehyde, phenol-aldehyde, furfural alcohol andfurfural. The resin-coated proppants can be either pre-cured or can becured by an overflush of a chemical binding agent, commonly known asactivator, once the proppants are in place.

Different binding agents have been used. U.S. Pat. Nos. 3,492,147 and3,935,339 disclose compositions and methods of coating solidparticulates with different resins. The particulates to be coatedinclude sand, nut shells, glass beads, and aluminum pellets. The resinsused include urea-aldehyde resins, phenol-aldehyde resins, epoxy resins,furfuryl alcohol resins, and polyester or alkyl resins. The resins canbe in pure form or mixtures containing curing agents, coupling agents orother additives. Other examples of resins and resin mixtures forproppants are described, for example, in U.S. Pat. Nos. 5,643,669;5,916,933; 6,059,034 and 6,328,105.

However, there are significant limitations to the use of resin-coatedproppants. For example, resin-coated proppants are much more expensivethan normal sands, especially considering that a fracturing treatmentusually employs tons of proppants in a single well. Normally, when theformation temperature is below 60° C., activators are required to makethe resin-coated proppants bind together. This increases the cost.

Thus, the use of resin-coated proppants is limited by their high cost toonly certain types of wells, or to use in only the final stages of afracturing treatment, also known as the “tail-in” of proppants, wherethe last few tons of proppants are pumped into the fracture. For lesseconomically viable wells, application of resin-coated proppants oftenbecomes cost prohibitive.

During hydrocarbon production, especially from poorly consolidatedformations, small particulates, typically of sand, often flow into thewellbore along with produced fluids. This is because the formation sandsin poorly consolidated formations, are bonded together with insufficientbond strength to withstand the forces exerted by the fluids flowingthrough, and are readily entrained by the produced fluids flowing out ofthe well.

The produced sand erodes surface and subterranean equipment, andrequires a removal process before the hydrocarbon can be processed.Different methods have been tried in an effort to reduce formation sandproduction. One approach employed is to filter the produced fluidsthrough a gravel pack retained by a screen in the wellbore, where theparticulates are trapped by the gravel pack. This technique is known asgravel packing. However, this technique is relatively time consuming andexpensive. The gravel and the screen can be plugged and eroded by thesand within a relatively short period of time.

Another method that has been employed in some instances is to injectvarious resins into a formation to strengthen the binding of formationsands. Such an approach, however, results in uncertainty and sometimescreates undesirable results. For example, due to the uncertainty incontrolling the chemical reaction, the resin may set in the wellboreitself rather than in the poorly consolidated producing zone. Anotherproblem encountered in the use of resin compositions is that the resinsnormally have short shelf lives. For example, it can lead to costlywaste if the operation using the resin is postponed after the resin ismixed.

Thus, it is highly desirable to have a cost effective composition and amethod that can control proppant flowback after fracturing treatment. Itis also highly desirable to have a composition and a method of reducingformation sand production from the poorly consolidated formation.

SUMMARY

The present invention in one embodiment relates to An aqueous slurrycomposition having water, particulates, a chemical compound forrendering the surface of the particulates hydrophobic and an oil.

The present invention in another embodiment relates to a method ofcontrolling sand in a hydrocarbon producing formation comprising thesteps of mixing water, particulates and a chemical compound forrendering the surface of the particulates hydrophobic, pumping themixture into the formation.

DETAILED DESCRIPTION OF THE INVENTION

Aggregation phenomena induced by hydrophobic interaction in water areobserved everywhere, in nature, industrial practice, as well as in dailylife. In general, and without being bound by theory, the hydrophobicinteraction refers to the attractive forces between two or more apolarparticles in water. When the hydrophobic interaction becomessufficiently strong, the hydrophobic particles come together to furtherreduce the surface energy, essentially bridging the particles togetherand resulting in the formation of particle aggregations, known ashydrophobic aggregations. It is also known that micro-bubbles attachedto hydrophobic particle surfaces also tend to bridge the particlestogether.

In this invention the concept of hydrophobic aggregation is applied todevelop compositions and methods to control proppant flowback as well asto reduce formation sand production during well production. Unlike inconventional approaches, where attention is focused on making proppantsor sand particles sticky through formation of chemical bonds betweenresins coated on the particle surfaces, in the present invention theattention is focused on making particle aggregations by bridging theparticles through strong hydrophobic force or micro-bubbles. Moreover,the hydrophobic surfaces of the particles induced by the presentcompositions reduce the friction between the particles and water makingthem harder to be entrained by fluids flowing out of the well.

In general, only a limited amount of agents is required in the presentinvention, and the field operational is simple.

There are different ways of carrying out the invention. For example,during a fracturing operation, a proppant, for example, sand, which isnaturally hydrophilic and can be easily water wetted, is mixed with afluid containing a chemical agent, referred as hydrophobizing agent,which makes the sand surface hydrophobic. The hydrophobizing agent canbe simply added into a sand slurry comprising sand and fracturing fluidwhich is pumped down the well. Depending on the hydrophobizing agentused and the application conditions, different fracturing fluids(aqueous or non-aqueous fluids) can be used. Aqueous fluid is normallypreferred. Of particular interest as a fracturing fluid, is water, orbrine or water containing a small amount of a friction reducing agent,also known as slick-water.

The hydrophobizing agent can be applied throughout the proppant stage orduring a portion of the proppant stage such as the last portion of theproppant stage, i.e., tail-in. Alternatively, sand can be hydrophobizedfirst and dried and then used to make a slurry and pumped into fracture.

It has been discovered that when a small amount of an oil, includinghydrocarbon oil and silicone oil, is mixed into the aqueous slurrycontaining the hydrophobized sands, the hydrophobic aggregation isenhanced significantly. The possible explanation for this is that theconcentration of oil among the hydrophobic sands may further enhance thebridge between sand grains.

The present invention can be used in a number of ways. For example, in afracture operation, proppant such as sand is mixed with a hydrophobizingagent in water based slurry and pumped into the fractures, and thenfollowed by over flush with oil or water containing a small amount ofoil to strengthen the bridge between the sand grains. Similarly, thesame operation can be applied in the tail-in stage. Alternatively theslurry containing a hydrophobizing agent can be pumped into the fractureforming the proppant pack, which can be further consolidated by oil orcondensate contained in the formation. Or the pre-hydrophobized sand isused as proppant and then followed by flushing with water, containingsmall amount of oil. Or the pre-hydrophobized sand is used as proppantwhich can be further consolidated by oil or condensate contained in theformation. Or the pre-hydrophobized sand is tailed in and followed byflushing with water containing small amount of oil. In all suchoperations, a gas such as nitrogen, carbon dioxide or air can be mixedinto the fluid.

There are different ways of pre-treating the solid surface hydrophobic.For example, one may thoroughly mix the proppants, preferable sands,with a fluid containing the appropriate hydrophobizing agent for certainperiod of time. After the proppant grains are dried, they can be used infracturing operations. Different fluids can be used. Differenthydrophobizing agents may need different conditions to interact with thesolid surface. When an aqueous fluid is used, the pH of the fluid mayalso play a role.

Besides controlling proppant flowback in hydraulic fracturingtreatments, the present invention is also useful in reducing formationsand production during well production. In the majority of cases, sandproduction increases substantially when wells begin to produce water.The formation sand is normally hydrophilic, or water-wet, and thereforeis easily entrained by a flowing water phase. Depending on thehydrophobizing agent used and the operational conditions, differentcarrying fluids, aqueous or non-aqueous, can be used. There aredifferent methods, according to the present invention, to treat aformation to reduce formation sand production. For example, a fluid,preferably an aqueous fluid, containing an appropriate amount ofhydrophobizing agent can be injected into the poorly consolidatedformation. After the sand grains become hydrophobic they tend toaggregate together. The hydrophobic surfaces also reduce the draggingforce exerted by the aqueous fluid making them more difficult to beentrained by the formation fluid. If the water phase contains certainamount of oil, the hydrophobic aggregation between sand grains can befurther enhanced. Alternatively, the fluid contain the hydrophobizingagent can be first injected into the poorly consolidated formation, andthen followed by injecting small volume of oil or a fluid containingoil. In all these applications, a gas such as nitrogen, carbon dioxideor air can be mixed into the fluid.

Also, the compositions and methods of the present invention can be usedin gravel pack operations, where the slurry containing hydrophobisedsands are added in the well bore to remediate sand production.

There are various types of hydrophobizing agents for sand, which can beused in the present invention. For example, it is known that manyorganosilicon compounds including organosiloxane, organosilane,fluoro-organosiloxane and fluoro-organosilane compounds are commonlyused to render various surfaces hydrophobic. For example, see U.S. Pat.Nos. 4,537,595; 5,240,760; 5,798,144; 6,323,268; 6,403,163; 6,524,597and 6,830,811 which are incorporated herein by reference for suchteachings.

Organosilanes are compounds containing silicon to carbon bonds.Organosiloxanes are compounds containing Si—O—Si bonds. Polysiloxanesare compounds in which the elements silicon and oxygen alternate in themolecular skeleton, i.e., Si—O—Si bonds are repeated. The simplestpolysiloxanes are polydimethylsiloxanes.

Polysiloxane compounds can be modified by various organic substituteshaving different numbers of carbons, which may contain N, S, or Pmoieties that impart desired characteristics. For example, cationicpolysiloxanes are compounds in which organic cationic groups areattached to the polysiloxane chain, either at the middle or the end.Normally the organic cationic group may contain a hydroxyl group orother functional groups containing N or O. The most common organiccationic groups are alkyl amine derivatives including secondary,tertiary and quaternary amines (for example, quaternary polysiloxanesincluding, quaternary polysiloxanes including mono- as well as,di-quaternary polysiloxanes, amido quaternary polysiloxanes, imidazolinequaternary polysiloxanes and carboxy quaternary polysiloxanes).

Similarly, the polysiloxane can be modified by organic amphotericgroups, where one or more organic amphoteric groups are attached to thepolysiloxane chain, either at the middle or the end, and include betainepolysiloxanes and phosphobetaine polysiloxanes.

Similarly, the polysiloxane can be modified by organic anionic groups,where one or more organic anionic groups are attached to thepolysiloxane chain, either at the middle or the end, including sulfatepolysiloxanes, phosphate polysiloxanes, carboxylate polysiloxanes,sulfonate polysiloxanes, thiosulfate polysiloxanes. The organosiloxanecompounds also include alkylsiloxanes includinghexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane,decamethylcyclopentasiloxane, hexamethyldisiloxane, hexaethyldisiloxane,1,3-divinyl-1,1,3,3-tetramethyldisiloxane, octamethyltrisiloxane,decamethyltetrasiloxane.

The organosilane compounds include alkylchlorosilane, for examplemethyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane,octadecyltrichlorosilane; alkyl-alkoxysilane compounds, for examplemethyl-, propyl-, isobutyl- and octyltrialkoxysilanes, andfluoro-organosilane compounds, for example,2-(n-perfluoro-octyl)-ethyltriethoxysilane, and perfluoro-octyldimethylchlorosilane.

Other types of chemical compounds, which are not organosiliconcompounds, which can be used to render particulate surface hydrophobicare certain fluoro-substituted compounds, for example certainfluoro-organic compounds including cationic fluoro-organic compounds.

Further information regarding organosilicon compounds can be found inSilicone Surfactants (Randal M. Hill, 1999) and the references therein,and in U.S. Pat. Nos. 4,046,795; 4,537,595; 4,564,456; 4,689,085;4,960,845; 5,098,979; 5,149,765; 5,209,775; 5,240,760; 5,256,805;5,359,104; 6,132,638 and 6,830,811 and Canadian Patent No. 2,213,168which are incorporated herein by reference for such teachings.

Organosilanes can be represented by the formulaRnSiX(_(4-n))  (I)wherein R is an organic radical having 1-50 carbon atoms that maypossess functionality containing N, S, or P moieties that impartsdesired characteristics, X is a halogen, alkoxy, acyloxy or amine and nhas a value of 0-3. Examples of organosilanes include:CH₃SiCl₃, CH₃CH₂SiCl₃, (CH₃)₂SiCl₂, (CH₃CH₂)₂SiCl₂, (C₆H₅)₂SiCl₂,(C₆H₅)SiCl₃, (CH₃)₃SiCl, CH₃HSiCl₂, (CH₃)₂HSiCl, CH₃SiBr₃, (C₆H₅)SiBr₃,(CH₃)₂SiBr₂, (CH₃CH₂)₂SiBr₂, (C₆H₅)₂SiBr₂, (CH₃)₃SiBr, CH₃HSiBr₂,(CH₃)₂HSiBr, Si(OCH₃)₄, CH₃Si(OCH₃)₃, CH₃Si(OCH₂CH₃)₃,CH₃Si(OCH₂CH₂CH₃)₃, CH₃Si[O(CH₂)₃CH₃]₃, CH₃CH₂Si(OCH₂CH₃)₃,C₆H₅Si(OCH₃)₂, C₆H₅CH₂Si(OCH₃)₃, C₆H₅Si(OCH₂CH₃)₃, CH₂═CHCH₂Si(OCH₃)₃,(CH₃)₂Si(OCH₃)₂, (CH₂═CH)Si(CH₃)₂Cl, (CH₃)₂Si(OCH₂CH₃)₂,(CH₃)₂Si(OCH₂CH₂CH₃)₂, (CH₃)₂Si[O(CH₂)₃CH₃]₂, (CH₃CH₂)₂Si(OCH₂CH₃)₂,(C₆H₅)₂Si(OCH₃)₂, (C₆H₅CH₂)₂Si(OCH₃)₂, (C₆H₅)₂Si(OCH₂CH₃)₂,(CH₂═CH)₂Si(OCH₃)₂, (CH₂═CHCH₂)₂Si(OCH₃)₂, (CH₃)₃SiOCH₃, CH₃HSi(OCH₃)₂,(CH₃)₂HSi(OCH₃), CH₃Si(OCH₂CH₂CH₃)₃, (CH₂═CHCH₂)₂Si(OCH₂CH₂OCH₃)₂,(C₆H₅)₂Si(OCH₂CH₂OCH₃)₂, (CH₃)₂Si(OCH₂CH₂OCH₃)₂,(CH₂═CH)₂Si(OCH₂CH₂OCH₃)₂, (CH₂═CHCH₂)₂Si(OCH₂CH₂OCH₃)₂,(C₆H₃)₂Si(OCH₂CH₂OCH₃)₂, CH₃Si(CH₃COO)₃, 3-aminotriethoxysilane,methyldiethylchlorosilane, butyltrichlorosilane, diphenyldichlorosilane,vinyltrichlorosilane, methyltrimethoxysilane, vinyltriethoxysilane,vinyltris(methoxyethoxy)silane, methacryloxypropyltrimethoxysilane,glycidoxypropyltrimethoxysilane, aminopropyltriethoxysilane,divinyldi-2-methoxysilane, ethyltributoxysilane,isobutyltrimethoxysilane, hexyltrimethoxysilane, n-octyltriethoxysilane,dihexyldimethoxysilane, octadecyltrichlorosilane,octadecyltrimethoxysilane, octadecyldimethylchlorosilane,octadecyldimethylmethoxysilane and quaternary ammonium silanes including3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride,3-(trimethoxysilyl)propyldimethyloctadecyl ammonium bromide,3-(trimethylethoxysilylpropyl)didecylmethyl ammonium chloride,triethoxysilyl soyapropyl dimonium chloride,3-(trimethylethoxysilylpropyl)didecylmethyl ammonium bromide,3-(trimethylethoxysilylpropyl)didecylmethyl ammonium bromide,triethoxysilyl soyapropyl dimonium bromide, (CH₃O)₃Si(CH₂)₃P⁺(C₆H₅)₃Cl⁻,(CH₃O)₃Si(CH₂)₃P⁺(C₆H₅)₃Br⁻, (CH₃O)₃Si(CH₂)₃P⁺(CH₃)₃Cl⁻,(CH₃O)₃Si(CH₂)₃P⁺(C₆H₁₃)₃Cl⁻, (CH₃O)₃Si(CH₂)₃N⁺(CH₃)₂C₄H₉Cl,(CH₃O)₃Si(CH₂)₃N⁺(CH₃)₂CH₂C₆H₅Cl⁻, (CH₃O)₃Si(CH₂)₃N⁺(CH₃)₂CH₂CH₂OHCl⁻,(CH₃O)₃Si(CH₂)₃N⁺(C₂H₅)₃Cl⁻, (C₂H₅O)₃Si(CH₂)₃N⁺(CH₃)₂C₁₈H₃₇Cl⁻.

Among different organosiloxane compounds which are useful for thepresent invention, polysiloxanes modified with organic amphoteric orcationic groups including organic betaine polysiloxanes and organicquaternary polysiloxanes are examples. One type of betaine polysiloxaneor quaternary polysiloxane is represented by the formula

wherein each of the groups R₁ to R₆, and R₈ to R₁₀ represents an alkylcontaining 1-6 carbon atoms, typically a methyl group, R₇ represents anorganic betaine group for betaine polysiloxane, or an organic quaternarygroup for quaternary polysiloxane, and have different numbers of carbonatoms, and may contain a hydroxyl group or other functional groupscontaining N, P or S, and m and n are from 1 to 200. For example, onetype of quaternary polysiloxanes is when R₇ is represented by the group

wherein R¹, R², R³ are alkyl groups with 1 to 22 carbon atoms or alkenylgroups with 2 to 22 carbon atoms. R⁴, R⁵, R⁷ are alkyl groups with 1 to22 carbon atoms or alkenyl groups with 2 to 22 carbon atoms; R⁶ is —O—or the NR⁸ group, R⁸ being an alkyl or hydroxyalkyl group with 1 to 4carbon atoms or a hydrogen group; Z is a bivalent hydrocarbon group withat least 4 carbon atoms, which may have a hydroxyl group and may beinterrupted by an oxygen atom, an amino group or an amide group; x is 2to 4; The R¹, R², R³, R⁴, R⁵, R⁷ may be the same or the different, andX— is an inorganic or organic anion including Cl⁻ and CH₃COO⁻. Examplesof organic quaternary groups include [R—N⁺(CH₃)₂—CH₂CH(OH)CH₂—O—(CH₂)₃—](CH₃COO⁻), wherein R is an alkyl group containing from 1-22 carbons oran benzyl radical and CH₃COO⁻ an anion. Examples of organic betaineinclude —(CH₂)₃—O—CH₂CH(OH)(CH₂)—N⁺(CH₃)₂CH₂COO⁻. Such compounds arecommercial available. Betaine polysiloxane copolyol is one of examples.It should be understood that cationic polysiloxanes include compoundsrepresented by formula (II), wherein R₇ represents other organic aminederivatives including organic primary, secondary and tertiary amines.

Other examples of organo-modified polysiloxanes include di-betainepolysiloxanes and di-quaternary polysiloxanes, where two betain orquaternary groups are attached to the siloxane chain. One type of thedi-betaine polysiloxane and di-quaternary polysiloxane can berepresented by the formula

wherein the groups R₁₂ to R₁₇ each represents an alkyl containing 1-6carbon atoms, typically a methyl group, both R₁₁ and R₁₈ group representan organic betaine group for di-betaine polysiloxanes or an organicquaternary group for di-quaternary, and have different numbers of carbonatoms and may contain a hydroxyl group or other functional groupscontaining N, P or S, and m is from 1 to 200. For example, one type ofdi-quaternary polysiloxanes is when R₁₁ and R₁₈ are represented by thegroup

wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, Z, X⁻ and x are the same as definedabove. Such compounds are commercially available. Quaternium 80 (INCI)is one of the commercial examples.

It will be appreciated by those skilled in the art that cationicpolysiloxanes include compounds represented by formula (III), whereinR₁₁ and R₁₈ represents other organic amine derivatives including organicprimary, secondary and tertiary amines. It will be apparent to thoseskilled in the art that there are different mono- and di-quaternarypolysiloxanes, mono- and di-betaine polysiloxanes and otherorgano-modified polysiloxane compounds which can be used to render thesolid surfaces hydrophobic and are useful in the present invention.These compounds are widely used in personal care and other products, forexample as discussed in U.S. Pat. Nos. 4,054,161; 4,654,161; 4,891,166;4,898,957; 4,933,327; 5,166,297; 5,235,082; 5,306,434; 5,474,835;5,616,758; 5,798,144; 6,277,361; 6,482,969; 6,323,268 and 6,696,052which are incorporated herein by reference.

Another example of organosilicon compounds which can be used in thecomposition of the present invention are fluoro-organosilane orfluro-organosiloxane compounds in which at least part of the organicradicals in the silane or siloxane compounds are fluorinated. Suitableexamples are fluorinated chlorosilanes or fluorinated alkoxysilanesincluding 2(n-perfluoro-octyl)ethyltriethoxysilane,perfluoro-octyldimethylchlorosilane, (CF₃CH₂CH₂)₂Si(OCH₃)₂,CF₃CH₂CH₂Si(OCH₃)₃, (CF₃CH₂CH₂)₂Si(OCH₂CH₂OCH₃)₂ andCF₃CH₂CH₂Si(OCH₂CH₂OCH₃)₃ and(CH₃O)₃Si(CH₂)₃N⁺(CH₃)₂(CH₂)₃NHC(O)(CF₂)₆CF₃Cl⁻. Other compounds whichcan be used, but less preferable, are fluoro-substituted compounds,which are not organic silicon compounds, for example, certainfluoro-organic compounds.

The following provides several non-limiting examples of compositions andmethods according to the present invention.

Example 1

300 g of 20/40 US mesh frac sand was added into 1000 ml of watercontaining 2 ml of a solution containing 20 vol % Tegopren 6924, adi-quaternary polydimethylsiloxane from Degussa Corp., and 80 vol % ofethylene glycol mono-butyl ether, and 1 ml of TEGO Betaine 810,capryl/capramidopropyl betaine, an amphoteric hydrocarbon surfactantfrom Degussa Corp. The slurry was shaken up and then let stand to allowsands settle down. When tilted slowly, the settled sand tended to moveas cohesive masses. After 10 ml of silicon oil, where its viscosity is200 cp, was mixed into the slurry and shaken up sand grains werevisually observed to clump together forming strong bridge among eachother.

The solution was decanted, and the sand was dried overnight at the roomtemperature for further tests.

Example 2

200 g of pre-treated sand according to Example 1 was placed in a fluidloss chamber to form a sand pack and wetted with water. Afterward, 300ml of water was allowed to filter from the top through the sand pack.The time was stopped when water drops slowed to less than one every fiveseconds. Same test using untreated sand was carried out as thereference. The average filter time over 6 runs for the pre-treated sandwas 2 minutes and 5 seconds, while it was 5 minutes for the untreatedsand.

Example 3

200 g of pre-treated sand according to Example 1 was placed in a fluidloss chamber to form a sand pack and wetted with kerosene. Afterward,300 ml of kerosene was allowed to filter from the top through the sandpack. The time was stopped when kerosene drops slowed to less than oneevery five seconds. Same test using untreated sand was carried out asthe reference. The average filter time over 5 runs for the pre-treatedsand was 3 minutes and 2 seconds, while it was 3 minutes and 28 secondsfor the untreated sand.

Example 4

100 ml of water and 25 grams of 30/50 US mesh fracturing sands wereadded into each of two glass bottles (200 ml). The first sample was usedas the reference. In the second sample, 2 ml of a solution containing20% Tegopren 6924 and 80% of ethylene glycol mono-butyl ether, and 0.5ml of kerosene were added. The slurry was shaken up and then let standto allow sands settle down. When tilted slowly, the settled sand tendedto move as cohesive masses. Sand grains were visually observed to clumptogether forming strong bridge among each others.

Example 5

100 ml of water and 25 grams of 30/50 US mesh fracturing sands wereadded into each of two glass bottles (200 ml). The first sample was usedas the reference. In the second sample, 2 ml of a solution containing20% Tegopren 6924 and 80% of ethylene glycol mono-butyl ether, and 0.5ml of frac oil were added. The slurry was shaken up and then let standto allow sands settle down. When tilted slowly, the settled sand tendedto move as cohesive masses. Sand grains were visually observed to clumptogether forming strong bridge among each others.

1. An aqueous slurry composition comprising: water; particulates; achemical compound for rendering the surface of the particulateshydrophobic; and an oil.
 2. The composition of claim 1, wherein thechemical compound is an organo-siloxane having the formula

wherein each of R₁ to R₆ and R₈ to R₁₀, represents an organic radicalcontaining 1-6 carbon atoms, R₇ represents an organic amphoteric groupfor an organic amphoteric polysiloxane or an organic cationic group foran organic cationic polysiloxane, and m and n are from 1 to
 200. 3. Thecomposition of claim 2, wherein the chemical compound is an organicamphoteric polysiloxane.
 4. The composition of claim 3, wherein thechemical compound is an organic amphoteric polysiloxane, and the valuesof m and n are from 1 to
 100. 5. The composition of claim 4, wherein thechemical compound is an organic amphoteric polysiloxane, wherein each ofR₁ to R₆ and R₈ to R₁₀ is a methyl group and the values of m and n arefrom 1 to
 100. 6. The composition of claim 2, wherein the chemicalcompound is an organic cationic polysiloxane.
 7. The composition ofclaim 6, wherein the chemical compound is an organic cationicpolysiloxane, and the values of m and n are from 1 to
 100. 8. Thecomposition of claim 7, wherein the chemical compound is an organiccationic polysiloxane, and each of R₁ to R₆ and R₈ to R₁₀ is a methylgroup and the values of m and n are from 1 to
 100. 9. The composition ofclaim 1, wherein the chemical compound is an organo-siloxane having theformula

where R₁₂ to R₁₇ each represents an organic radical containing 1-6carbon atoms, one of R₁₁ and R₁₈ represents an organic amphoteric groupand the other of R₁₁ and R₁₈ represents an organic amphoteric group oran organic radical for a di-amphoteric polysiloxane or one of R₁₁ andR₁₈ represents an organic cationic group and the other of R₁₁ and R₁₈represents an organic cationic group or an organic radical for adi-cationic polysiloxane, and m is 1 to
 200. 10. The composition ofclaim 9, wherein the chemical compound is a di-amphoteric polysiloxane.11. The composition of claim 10, wherein the chemical compound is adi-amphoteric polysiloxane and the values of m are from 1 to
 100. 12.The composition of claim 11, wherein each of R₁₂ to R₁₇ represents amethyl group and the m is from 1 to
 100. 13. The composition of claim 8,wherein the chemical compound is a di-cationic polysiloxane.
 14. Thecomposition of claim 13, wherein the chemical compound is a di-cationicpolysiloxane, and the values of m are from 1 to
 100. 15. The compositionof claim 14, wherein each of R₁₂ to R₁₇ represents a methyl group andthe m is from 10 to
 100. 16. The composition of claim 1, wherein thechemical compound is an organosilane having the formulaR_(n)SiX_((4-n)) wherein R is an organic radical having 1-50 carbonatoms, X is a halogen, alkoxy, acyloxy or amine and n has a value of1-3.
 17. The composition of claim 16, wherein the organosilane isselected from the group consisting of: CH₃SiCl₃, CH₃CH₂SiCl₃,(CH₃)₂SiCl₂, (CH₃CH₂)₂SiCl₂, (C₆H₅)₂SiCl₂, (C₆H₅)SiCl₃, (CH₃)₃SiCl,CH₃HSiCl₂, (CH₃)₂HSiCl, CH₃SiBr₃, (C₆H₅)SiBr₃, (CH₃)₂SiBr₂,(CH₃CH₂)₂SiBr₂, (C₆H₅)₂SiBr₂, (CH₃)₃SiBr, CH₃HSiBr₂, (CH₃)₂HSiBr,Si(OCH₃)₄, CH₃Si(OCH3)₃, CH₃Si(OCH₂CH₃)₃, CH₃Si(OCH₂CH₂CH₃)₃,CH₃Si[O(CH₂)₃CH₃]₃, CH₃CH₂Si(OCH₂CH₃)₃, C₆H₅Si(OCH₃)₃, C₆H₅CH₂Si(OCH₃)₃,C₆H₅Si(OCH₂CH₃)₃, CH₂═CHCH₂Si(OCH₃)₃, (CH₃)₂Si(OCH₃)₂,(CH₃)₂Si(OCH₂CH₃)₂, (CH₃)₂Si(OCH₂CH₂CH₃)₂, (CH₃)₂Si[O(CH₂)₃CH₃]₂,(CH₃CH₂)₂Si(OCH₂CH₃)₂, (C₆H₅)₂Si(OCH₃)₂, (C₆H₅CH₂)₂Si(OCH₃)₂,(C₆H₅)₂Si(OCH₂CH₃)₂, (CH₂═CH)₂Si(OCH₃)₂, (CH₂═CHCH₂)₂Si(OCH₃)₂,(CH₃)₃SiOCH₃, CH₃HSi(OCH₃)₂, (CH₃)₂HSi(OCH₃), CH₃Si(OCH₂CH₂CH₃)₃,(CH₂═CHCH₂)₂Si(OCH₂CH₂OCH₃)₂, (C₆H₅)₂Si(OCH₂CH₂OCH₃)₂,(CH₃)₂Si(OCH₂CH₂OCH₃)₂, (CH₂═CH)₂Si(OCH₂CH₂OCH₃)₂,(CH₂═CHCH₂)₂Si(OCH₂CH₂OCH₃)₂, (C₆H₅)₂Si(OCH₂CH₂OCH₃)₂, CH₃Si(CH₃COO)₃,methyldiethylchlorosilane, butyltrichlorosilane diphenyldichlorosilane,vinyltrichlorosilane, methyltrimethoxysilane, vinyltriethoxysilane,vinyltris(methoxyethoxy)silane, methacryloxypropyltrimethoxysilane,glycidoxypropyltrimethoxysilane, aminopropyltriethoxysilane,divinyldi-2-methoxysilane, ethyltributoxysilane,isobutyltrimethoxysilane, hexyltrimethoxysilane, n-octyltriethoxysilane,dihexyldimethoxysilane; trichloro-octadecylsilane,3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride,3-(trimethylethoxysilylpropyl)didecylmethyl ammonium chloride andtriethoxysilyl soyapropyl dimonium chloride.
 18. The composition ofclaim 1 further comprising a gas.
 19. The composition of claim 18,wherein the gas is selected from the group consisting of air, nitrogen,carbon dioxide, methane and mixtures thereof.
 20. The composition ofclaim 1, wherein the oil is selected from the group consisting of ahydrocarbon oil, a silicon oil, kerosene oil, a frac oil andcombinations thereof.
 21. The composition of claim 1, wherein theparticulates are selected from the group consisting of sand, resincoated sand, synthetic polymeric beads, ceramic, glass spheres,carbonate and bauxite particulates.
 22. The composition of claim 1,wherein the particulates are sands.
 23. The composition of claim 1,wherein the chemical compound is selected from the group consisting ofan organosilane, an organosiloxane, a fluoro-organosilane, afluoro-organosiloxane, a fluoro-organic compound and combinationsthereof.
 24. The composition of claim 1, wherein the chemical compoundis selected from the group consisting of polysiloxanes modified with oneor more organic cationic groups, polysiloxanes modified with one or moreorganic amphoteric groups, polysiloxanes modified with one or moreorganic anionic groups, amine silanes and combinations thereof.
 25. Thecomposition of claim 1, wherein the chemical compound is selected fromthe group consisting of polysiloxanes modified with one or more organiccationic groups.
 26. The composition of claim 1, wherein the chemicalcompound is selected from the group consisting of polysiloxanes modifiedwith one or more organic amphoteric groups.
 27. The composition of claim1, wherein the chemical compound is a fluoro-organic compound.
 28. Thecomposition of claim 1, wherein the chemical compound is afluoro-organosilane.
 29. The composition of claim 1, wherein thechemical compound is selected from the group consisting of2-(n-perfluoro-octyl)ethyltriethoxysilane,perfluoro-octyldimethylchlorosilane, (CF₃CH₂CH₂)₂Si(OCH₃)₂,CF₃CH₂CH₂Si(OCH₃)₃, (CF₃CH₂CH₂)₂Si(OCH₂CH₂OCH₃)₂ andCF₃CH₂CH₂Si(OCH₂CH₂OCH₃)₃ and(CH₃O)₃Si(CH₂)₃N⁺(CH₃)₂(CH₂)₃NHC(O)(CF₂)₆CF₃Cl⁻.
 30. The composition ofclaim 1, wherein the chemical compound is a cationic fluoro-organiccompound.
 31. The composition of claim 1, wherein the chemical compoundis a fluoro-organosiloxane.
 32. A method of controlling proppantflowback in a hydrocarbon producing formation comprising the steps of:mixing water, particulates, a chemical compound for rendering thesurface of the particulates hydrophobic and an oil; and pumping themixture into the formation.
 33. The method of claim 32, wherein thechemical compound is selected from the group consisting of anorganosilane, an organosiloxane, a fluoro-organosilane, afluoro-organosiloxane and a fluoro-organic compound.
 34. The method ofclaim 33, wherein the chemical compound is an organo-polysiloxane havingthe formula

wherein each of R₁ to R₆ and R₈ to R₁₀, represents an organic radicalcontaining 1-6 carbon atoms, R₇ represents an organic-amphoteric groupfor an organic amphoteric polysiloxane or an organic cationic group foran organic cationic polysiloxane, and m and n are from 1 to
 200. 35. Themethod of claim 34, wherein the particulates are sands.
 36. The methodof claim 33, wherein the chemical compound is an organosilane having theformulaR_(n)SiX_((4-n)) wherein R is an organic radical having 1-50 carbonatoms, X is a halogen, alkoxy, acyloxy or amine and n has a value of1-3.
 37. The method of claim 33, wherein the chemical compound is anorgano-siloxane having the formula

where R₁₂ to R₁₇ each represents an organic radical containing 1-6carbon atoms, one of R₁₁, and R₁₈ represents an organic amphoteric groupand the other of R₁₁ and R₁₈ represents an organic amphoteric group oran organic radical for a di-betaine polysiloxane or an organic cationicgroup for a di-cationic polysiloxane, and m is 1 to
 200. 38. The methodof claim 32, including the step of subjecting the mixture to shear inthe presence of a gas.
 39. The method of claim 38, wherein the gas isselected from the group consisting of air, nitrogen, carbon dioxide,methane and mixtures thereof.
 40. The method of claim 32, wherein theparticulates are selected from the group consisting of sand, resincoated sand, ceramic, synthetic polymeric beads and bauxiteparticulates.
 41. The method of claim 32, wherein the particulates aresands.
 42. The method of claim 32, wherein the oil is selected from thegroup consisting of a hydrocarbon oil, a silicone oil, kerosene oil, afrac oil and combinations thereof.
 43. The method of claim 32, whereinthe chemical compound is selected from the group consisting ofpolysiloxanes modified with one or more organic cationic groups.
 44. Themethod of claim 32, wherein the chemical compound is selected from thegroup consisting of polysiloxanes modified with one or more organicamphoteric groups.
 45. The method of claim 32, wherein the chemicalcompound is a fluoro-organic compound.
 46. The method of claim 32,wherein the chemical compound is a fluoro-organosilane.
 47. The methodof claim 32, wherein the chemical compound is selected from the groupconsisting of 2-(n-perfluoro-octyl)ethyltriethoxysilane,perfluoro-octyldimethylchlorosilane, (CF₃CH₂CH₂)₂Si(OCH₃)₂,CF₃CH₂CH₂Si(OCH₃)₃, (CF₃CH₂CH₂)₂Si(OCH₂CH₂OCH₃)₂ andCF₃CH₂CH₂Si(OCH₂CH₂OCH₃)₃ and(CH₃O)₃Si(CH₂)₃N⁺(CH₃)₂(CH₂)₃NHC(O)(CF₂)₆CF₃Cl⁻.
 48. The method of claim32, wherein the chemical compound is a cationic fluoro-organic compound.49. The method of claim 32, wherein the chemical compound is afluoro-organosiloxane.
 50. The method of claim 32, wherein the chemicalcompound is an amine silane.
 51. A method of controlling proppantflowback in a hydrocarbon producing formation comprising the steps of:contacting particulates with a medium containing a chemical compound torender the surface of the particulates hydrophobic, separating theparticulate from the medium; and blending the hydrophobic particulatewith water and an oil to form a mixture; and pumping the mixture intothe formation.
 52. The method of claim 51, wherein the chemical compoundis an organo-polysiloxane having the formula

wherein each of R₁ to R₆ and R₈ to R₁₀, represents an organic radicalcontaining 1-6 carbon atoms, R₇ represents an organic amphoteric groupfor an organic amphoteric polysiloxane or an organic cationic group foran organic cationic polysiloxane, and m and n are from 1 to
 200. 53. Themethod of claim 52, wherein the particulates are sands.
 54. The methodof claim 51, wherein the chemical compound is an organo-siloxane havingthe formula

where R₁₂ to R₁₇ each represents an organic radical containing 1-6carbon atoms, one of R₁₁ and R₁₈ represents an organic amphoteric groupand the other of R₁₁ and R₁₈ represents an organic amphoteric group oran organic radical for a di-betaine polysiloxane or one of R₁₁ and R₁₈represents an organic cationic group and the other of R₁₁ and R₁₈represents an organic cationic group or an organic radical for adi-cationic polysiloxane, and m is 1 to
 200. 55. The method of claim 51,including the step of subjecting the mixture to shear in the presence ofa gas.
 56. The method of claim 51, wherein the gas is selected from thegroup consisting of air, nitrogen, carbon dioxide, methane and mixturesthereof.
 57. The composition of claim 51, wherein the particulates aresands.
 58. The composition according to claim 51, wherein the oil isselected from the group consisting of a hydrocarbon oil, a silicone oil,kerosene oil, a frac oil and combinations thereof.
 59. The method ofclaim 51, wherein the chemical compound is selected from the groupconsisting of polysiloxanes modified with one or more organic cationicgroups.
 60. The method of claim 51, wherein the chemical compound isselected from the group consisting of polysiloxanes modified with one ormore organic amphoteric groups.
 61. The method of claim 51, wherein thechemical compound is a fluoro-organic compound.
 62. The method of claim51, wherein the chemical compound is a fluoro-organosilane.
 63. Themethod of claim 51, wherein the chemical compound is afluoro-organosiloxane.
 64. The method of claim 51, wherein the chemicalcompound is selected from the group consisting of2-(n-perfluoro-octyl)ethyltriethoxysilane,perfluoro-octyldimethylchlorosilane, (CF₃CH₂CH₂)₂Si(OCH₃)₂,CF₃CH₂CH₂Si(OCH₃)₃, (CF₃CH₂CH₂)₂Si(OCH₂CH₂OCH₃)₂ andCF₃CH₂CH₂Si(OCH₂CH₂OCH₃)₃ and(CH₃O)₃Si(CH₂)₃N⁺(CH₃)₂(CH₂)₃NHC(O)(CF₂)₆CF₃Cl⁻.
 65. The method of claim51, wherein the chemical compound is a cationic fluoro-organic compound.66. The method of claim 51, wherein the chemical compound is an aminesilane.